1+2+3+...+x=78
=>(x+1)x:2=78
=>x2+x=156
=>x2+13x-12x-156=0
=>x(13+x)-12(x+13)=0
=>(x-12)(x+13)=0
=>x-12=0 hoặc x+13=0
=>x=12 hoặc x=-13
vì x>0 =>x=12
vậy x=12
1+2+3+..................+x=78
tim giup minh x nha.
Tim x
a) ( x - 78) .26 =40
b) 39 . (x-5) =39
c) 30- ( 52 - x) =90
d) (x-12) : 5 =2
tim x :
a) (3x - 4) . (x- 1)3 = 0
b) x17 = x
c) 22x - 1 : 4 = 83
d) (x + 2)5 = 210
e) (X - 5)4 = (X - 5)6
f) 1+2+3+.......+x =78
g) (x +1)2 =(x +1)0
h) (2 + x) + (4 +x) + ( 6 +x) +.......+(52 + x)= 780
Tìm x
Trả lời nhanh giúp mình nha, mnh đang rất vội, cảm ơn.
Tim x ,biet :
(x-78):70=0
(x-2)x (2x-10)=0
2x(x-5)=0
2x(x-6) =0
(x-15)x15=0
tính va tim x:
a,36.72-36.67
b,{296:[78-(579-30.7):9]}.18
c,3x-5=16
d,42-2.(32-2x+1)=10
GIUP MINH
Tìm y(k tim x đâu nha)
52 x (y : 78 ) = 3380
Bai 1: Tinh nhanh:
a, -69+53+46+(-14)+78 b, 13-12+11+10-9+8-7-6+5-4+3+2-1
Bai 2: a,Tim gia tri nho nhat cua bieu thuc: A= |x+19|+|y-5|+1890
b, Tim gia tri lon nhat cua bieu thuc: B= -|x-7|-|y+13|+1945
Bai 3: Tim x,y thuoc Z biet: a, xy-3x= -19 b, 3x+4y-xy= 16
Bai 4: Tim x thuoc Z biet: a, x.(x+3)= 0 b, (x-2) (5-x)= 0 c, (x+1) (x2+1)= 0
d, -12 (x-5)+7 (3-x)= 5 e, 30 (x+2)-6 (x-5)-24x= 100 f, (x+1)+(x+3)+(x+5)+. . .+(x+99)= 0
Minh xin cam on truoc ! THANK YOU
Tìm x biết : 2^x+1 - 2^x+3+2^x+5=78
tìm x biết: 1+2+3+....+x=78
